Nu-morpholine-beta-ethyl hydrazine and acid addition salts thereof



United States Patent Ofilice 3,085,975 Patented Apr. 23, 1963 3,086,975 N-MORPHOLINE-BETA-ETHYL HYDRAZINE AND ACID ADDITION SALTS THEREOF Alfred Halpern, Great Neck, Lake Success, N.Y., assignor to Synergistics, Inc, New York, N.Y., a corporation of New York No Drawing. Filed Oct. 11, 1960, Ser. No. 61,830 3 Claims. (Cl. 260-247.5)

This invention relates to heterocyclic alkyl hydrazine compounds which are useful both as intermediates for the preparation of therapeutic compounds as Well as to treat certain pathologic entities. More particularly, this invention is concerned with N-morpholine-beta-ethyl hydazine and its acid addition salts as Well as the methods for their preparation.

The study of the metabolism of the physiologic stressor amines (epinephrine, nor-epinephrine and serotonin) has shown that these substances are substrates for the monoamine oxidase enzyme system. These stressor amines appear to be implicated in central nervous system and autonomic nervous system activity as well as cardiac function and to exert pronounced vascular actions and other physiologic responses.

Both monoamine oxidase and its substrate are found in high levels in the hypothalamus, and it has been suggested that the amine substrate compounds play an important role in neuro-transmi-ssion somewhat similar to acetylcholine. It has been postulated that certain malfunctioning of the central nervous system is due to the depletion of the neurohumoral agents by their too rapid destruction by the monoamine oxidase system. Thus, for example, the therapy for true depressions has been previously limited to the replacement of these amines by the administration of central nervous system-acting amine compounds (sympathomimetic amiens) for the milder cases, although dectroconv'ulsive shock therapy has been required in addition for the severe depressions when suicidal tendencies were evident.

More recently the new therapeutic approach has been suggested which proposes to inhibit the enzymatic destruction of these stressor amines through the administration of specific chemical compounds which block the enzyme system. This blockade of the monoarnine oxidase system has afforded a new therapeutic horizon, offering new hope to those patients sufien'ng from diseases caused by an imbalance of the enzyme-substrate levels, through a biochemical-physiologic approach.

There are several groups of compounds which have been shown to selectively inhibit the enzymatic action of monoamine oxidase enzyme in vivo. These may be separated into two classes of compounds according to their duration of action. Those compounds exhibiting a long duration of action consist mainly of the hydrazine derivatives, and those compounds exhibiting a short duration of action consist of the Harrnala alkaloids and others of differing chemical structures (such as amphetamine).

Although for therapeutic reasons the long-acting class of monoamine oxidase inhibitors have been the preferred ones, these compounds have been shown to cause serious side reactions ranging from mild local tissue responses to death. The more commonly encountered side effects in the clinical usage of the hydrazine type of monoamine oxidase inhibitors have been hypotension, anemia and liver damage. Members of the short-acting group have also been reported to cause untoward reactions which limit their therapeutic use. The need for a safe, effective means to restore the physiologic neurohumoral balance has been noted many times.

It is important to note that virtually all of the monoamine oxidase inhibitor compounds are patterned after the structure of epinephrine (excepting the Harmala alkaloids). These compounds contain an unsaturated cyclic nucleus, and an alkyl side-chain of from 2-4 carbons, which is substituted in the beta-position by hydrazine. This structural relationship has given rise to a postulated mechanism of activity which describes these hydrazine derivatives as pseudo-amines acting to replace the physiologically active neurohumoral amines as an enzyme substrate. Although this mechanism oi action has not been universally accepted, other investigators have confirmed the close similarity between the physiologic behavior of the amine oxidase inhibitor compounds and the naturally occurring amine enzyme substrate.

The compounds of my invention, although hydrazine derivatives, are not related to physiologically occurring stressor amine compounds and do not possess the noxious side reactions which have been described for other hydrazine derivatives, and yet are potent amine-oxidase inhibitors. The compounds of my invention are heterocyclic derivatives comprising the heterocyclic nucleus of morpholine to which is attached an ethyl side-chain through the nitrogen atom of the morpholine ring as well as a hydrazine group. The base N-morpholine-beta'ethyl hydrazine has the following structural formula:

H10 N/CHI IIz NH ill:

N-morpholine-betaethyl-hydrazine is prepared through the reaction between hydrazine and N-morpholine-betaethyl chloride in alcoholic media. The compound is obtained as an oil which may be converted to a solid crystalline form by reaction with both pharmaceutically acceptable inorganic and organic acids. The hydrochloride of N-morpholine-beta-ethyl hydrazine melts at 9495 C. and analyzes in good agreement with the theoretical values for carbon, hydrogen, and nitrogen. (Theory: carbon, 40.0%; hydrogen, 7.8%, and nitrogen 23.3%. Found: carbon 39.8%; hydrogen 8.9%; and nitrogen, 23.0%. This acid salt of N-morpholinc-beta-ethyl hydrazine is soluble in water, methanol, and chloroform but is insoluble in ether, benzene, and acetone. The acid salts are stable and may be utilized in preparations of pharmaceutical dose forms for therapeutic use.

The reaction between N-morpholine-beta-ethyl chloride and hydrazine requires special precautions to achieve optimal yields of the desired compound. An excess of hydrazine should be maintained in the reaction media at all times. After completion of the reaction, specialized fractionation techniques are necessary to remove the interfering impurities which have very similar solubility and chemical properties to the desired compound. I have found that this fractional separation may be readily obtained through the use of chloroform which selectively removes the acid salt of the desired compound leaving the unreacted impurities.

When it is desired to utilize N-morpholine-beta-ethyl hydrazine or its salts in therapy, it may be administered in the form of a tablet or capsule, in a dosage range from 10 to 70 mg. per day administered in divided doses. For initial treatment, the preferred dosage is 30 to 50 mg. a day, administered in divided doses of 10 mg. each, and if more is required, an additonal 20 mg. may be administered at bedtime. Improvement should be seen within one week. After maximum benefit is attained,

established by determining the individual requirements of the patient.

The following examples illustrate my invention:

Example 1 In a round-bottom glass boiling flask, fitted with a reflux condenser, a stirring apparatus, and a heating mantle, is placed one liter of isopropyl alcohol containing 0.1 mole of hydrazine. The stirring is started and the solution heated to reflux temperature. As the solution begins to reflux, a mixture of 0.1 mole of N-morpholinebeta-ethyl chloride, dissolved in one liter of isopropyl alcohol, is added dropwise to the hydrazine solution. The refluxing is maintained for a period of from 12 to hours, after which the reaction mixture is allowed to cool to room temperature. The isopropyl alcohol solution is concentrated to two-thirds its original volume, whereupon two layers form. The unreacted material in the isopropyl alcohol solution is separated from the crude reaction product by means of a separatory funnel.

The oily reaction product is dissolved in one liter of 0.2 N sulfuric acid solution, filtered and neutralized with caustic soda. The oily layer is separated and dissolved in three volumes of chloroform. The aqueous layer is extracted twice with 100 cc. portions of chloroform, and the chloroform extracts are added to the bulk of the chloroform solution. The chloroform extract is dried over anhydrous sodium sulfate for 24 hours. To obtain the free base, the chloroform is evapo; rated under reduced pressure. The resulting oily material is Nmorpholine-beta-ethyl hydrazine. It analyzes for carbon, hydrogen and nitrogen as:

Found: C=49.2%; H:9.9%; N=29.3%.

Dry hydrogen chloride is then passed through the chloroform solution to form the hydrochloride salt which crystalizes slowly on standing. To accelerate the crystalizing process, the chloroform solution may be concentrated to one-tenth the original volume. The crystalline material is filtered, dried, and recrystalized from isopropyl alcohol until a constant melting point is obtained. The dry recrystalized N-morpholine-beta-ethyl hydrazine hydrochloride melts at 94 to 96 C. It analyzes for percent carbon, 39.8%; hydrogen, 8.0%; and nitrogen 23.0%, which is in good agreement with the theoretical values (carbon, 40.0%; hydrogen, 7.8%; and nitro gen 23.3%).

Nmorpholine-beta-ethyl hydrazine hydrochloride is soluble in water, methanol, ethanol, and chloroform is insoluble in ether, acetone, and benzene.

Example 2 In place of the N-morpholine-beta-ethyl chloride used in Example 1, above, there may be substituted other halogen analogues such as morpholine ethyl bromide or morpholine ethyl iodide. The other steps of the reaction remain the same.

Example 3 In place of the isopropyl alcohol used as the solvent in Example 1, above, may be substituted a member of the class of alcohols corresponding to the formula ROH, wherein R is a lower alkyl group with a carbon chain length of from 1 to 5 carbons. The other steps of the reaction remain the same.

Example 4 Pharmaceutically acceptable acid salts in addition to the hydrochloride described in Example 1 may be prepared from N-morpholine-beta-ethyl hydrazine by reacting the base compound with the appropriate pharmaceutically acceptable inorganic or organic acid in a suitable solvcnt. Examples of such acids are: acetic acid, butyric acid, benzoic acid, citric acid, fumaric acid, glucuronic acid, hydrobromic acid, hydroiodic acid, lauric acid, nicotinic acid, nitric acid, oleic acid, phosphoric acid, propionic acid, sacchoric acid, salicylic acid, succinic acid, and sulfuric acid. While the preferred solvent for this reaction is chloroform, a liquid alcohol having an alkyl chain length of from 2-6 carbons may be used, although the volumes required are often large to achieve solution. Any volatile polar organic solvent will be suitable. Ether and acetone may also be used as the solvent, but these require cooling to offset the exethermic reaction which occurs.

The acid salt is prepared either by treatment of the crude material obtained from the reaction in Example 1 above, without isolation of the free base or by liberating the free base from the acid salt obtained in the above Example 1 after purification. Whatever the start ing material for the preparation of the acid salt, the steps are essentially the same involving the neutralization with caustic soda, dissolving the base in an appropriate solvent for reaction, and the formation of the salt.

To the solution of the base in the selected anhydrous solvent is added an anhydrous solution of the organic or inorganic acid dissolved in the same solvent. When the hydrochloride, hydrobromide, or hydroiodide salts are desired, the anhydrous gas may be passed directly through the solution of the N-morpholine-beta-ethyl hydrazine. The ratio of reacting components is one mole of base to one mole of acid. When the addition of the acid group has been completed, the solvent is concentrated until crystallization begins and the whole set is put aside to cool in an ice-chest. The crystalline solid is filtered and dried. The dried material is then available for compounding into the appropriate pharmaceutical dosage form for use in therapy.

Example 5 When it is desired to utilize N-morpholine-beta-ethyl hydrazine or its salts in therapy, it may be administered in the form of a tablet or a capsule with a dosage range of from 10 to 70 mg. per day, administered in divided doses. For initial treatment, the preferred dosage is from 30 to 50 mg. a day, administered in divided doses of 10 mg. each, and if more is required, an additional 20 mg. may be administered at bedtime.

The products of my invention may be used preferably in therapy, either as a tablet or as a capsule. These pharmaceutical forms are prepared in the usual manner, utilizing the active ingredient of either Nmorpholinebeta-ethyl hydrazine or one of its salts. While a dosage range of from 1 to 30 mg. may be utilized in each in,

dividual unit dose, the optimal content is 5 mg. per capsule or tablet.

The preparation of tablets or capsules of the salts of N-morpholine-beta-ethyl hydrazine for therapeutic use requires no special processing techniques and may contain in addition to the active ingredients the usual inert pharmaceutical carriers or diluents, binding and granulating agents necessary for proper tablet formulation. Because of the stability of the active ingredients, there is no incompatability between the well-known tableting materials and the products of my invention.

In preparing a tablet from the oily base compound of N-morpholine-beta-ethyl hydrazine, the active compound is first dispersed in a solid pharmaceutical carrier or diluent, such as lactose or starch, and then mixed with the necessary pharmaceutical binders and granulating agents. A recommended ratio of active ingredient to diluent is from one part of the active base compound to 50 parts of the diluent, to one part of the active base compound to parts of the diluent, dependent upon the nature and size of the dose-form selected. Thus, a tablet would utilize the lower ratio while a capsule may require lllC larger 5 one. The granulating and compressing step of the tablet manufacture remains the same.

A liquid-filled gelatine capsule may also be prepared from the base compound by either filling the oily base material directly into the gelatine capsule so that each contains the preferred unit dose range of from 1 to 10 mg. per capsule or by first dissolving the base compound in an inert carrier, such as propylene glycol, glycerin, or vegetable oil, and then filling into an appropriate capsule so that each unit contains the optimal dosage range of from 1 to 10 mg.

What is claimed is:

l. A compound selected from the group consisting of N-morpholine-beta'ethyl hydrazine, and its non-toxic pharmaceutically acceptable acid addition salts.

2. N-morpholine-beta-eth3l hydrazine.

3. N-morpholine-beta-ethyl hydrazine hydrochloride.

References Cited in the file of this patent UNITED STATES PATENTS 2,830,050 Biel Apr. 8, 1958 2,937,118 Haxthauseri et al May 17, 1960 2,953,494 Cook et a1 Sept. 20, 1960 2,955,108 Ornietanski Oct. 4, 1960 2,957,873 Rudner Oct. 25, 1960 2,970,145 De Benneville Jan. 31, 1961 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF N-MORPHOLINE-BETA-ETHYL HYDRAZINE, AND ITS NON-TOXIC PHARMACEUTICALLY ACCEPTABLE ACID ADDITION SALTS. 